Free testosterone calculator

Quickly and easily calculate both free and bioactive testosterone levels, by inputting laboratory values for total testosterone, albumin and SHBG.

Free and bioactive testosterone levels more accurately reflect true androgen status than total testosterone levels.

Enter values for total testosterone, albumin and sex hormone binding globulin (SHBG), obtained from blood testing, and the tool will calculate free and bioactive testosterone levels.

A symptomatic response to T therapy is generally seen within 3 months. Monitoring should occur at least 2-3 times during the first year, and 1-2 times per year thereafter. Monitoring should include serum T, PSA levels, haematocrit/haemoglobin, liver function tests and lipid profile.

 

* References: Traish et al. Testosterone Deficiency, The American Journal of Medicine (2011) 124, 578-587. Nebido (testosterone undecanoate) EMC Summary of Product Characteristics March 2020: https:// www.medicines.org.uk/emc/product/3873 (Accessed September 2020)

 

Using a value of 3.6 x 104 L/mol for the association constant of albumin for T, the calculated albumin-bound T varied from 7.14 nmol/L (40 g/L albumin) to 7.80 nmol/L (50 g/L albumin). In view of the relatively unimportant changes in FT, when the albumin concentration varies by as much as 25%, it was concluded that for routine purposes FT could be calculated assuming an albumin concentration of 43 g/L (6.2 x 10-4 mol/L) if one is not dealing with sera from patients with marked abnormalities in plasma protein composition, such as in nephrotic syndrome or cirrhosis of the liver, or with sera obtained during pregnancy, in which cases the actual albumin concentration should be taken into account.

 

**References: Vermeulen et al., A critical evaluation of simple methods for the estimation of free testosterone in serum, J Clin Endocrinol Metab (1999) 84(10): 3666-72

d) A symptomatic response to T therapy is generally seen within 3 months. Monitoring should occur at least 2-3 times during the first year, and 1-2 times per year thereafter. Monitoring should include serum T, PSA levels, and hematocrit/ hemoglobin. There is no need to measure liver or renal function tests for any of the routine T-therapy formulations.

* References: Traish et al. Testosterone Deficiency, The American Journal of Medicine (2011) 124, 578-587

 

g) Using a value of 3.6 x 104 L/mol for the association constant of albumin for T, the calculated albumin-bound T varied from 7.14 nmol/L (40 g/L albumin) to 7.80 nmol/L (50 g/L albumin). In view of the relatively unimportant changes in FT, when the albumin concentration varies by as much as 25%, it was concluded that for routine purposes FT could be calculated assuming an albumin concentration of 43 g/L (6.2 x 10-4 mol/ L) if one is not dealing with sera from patients with marked abnormalities in plasma protein composition, such as in nephrotic syndrome or cirrhosis of the liver, or with sera obtained during pregnancy, in which cases the actual albumin concentration should be taken into account.

** References: Vermeulen et al., A critical evaluation of simple methods for the estimation of free testosterone in serum, J Clin Endocrinol Metab (1999) 84(10): 3666-72

Using a value of 3.6 x 104 L/mol for the association constant of albumin for T, the calculated albumin-bound T varied from 7.14 nmol/L (40 g/L albumin) to 7.80 nmol/L (50 g/L albumin). In view of the relatively unimportant changes in FT, when the albumin concentration varies by as much as 25%, it was concluded that for routine purposes FT could be calculated assuming an albumin concentration of 43 g/L (6.2 x 10-4 mol/L) if one is not dealing with sera from patients with marked abnormalities in plasma protein composition, such as in nephrotic syndrome or cirrhosis of the liver, or with sera obtained during pregnancy, in which cases the actual albumin concentration should be taken into account1.

A symptomatic response to T therapy is generally seen within 3 months. Monitoring should occur at least 2-3 times during the first year, and 1-2 times per year thereafter. Monitoring should include serum T, PSA levels, and hematocrit/ hemoglobin. There is no need to measure liver or renal function tests for any of the routine T-therapy formulations2.

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References

  • Vermeulen et al., A critical evaluation of simple methods for the estimation of free testosterone in serum, J Clin Endocrinol Metab (1999) 84(10): 3666-72 Return to content
  • Traish et al., Testosterone Deficiency, The American Journal of Medicine (2011) 124, 578-587 Return to content